L. H. Morin disclosed a combination lock with concealed resettable control in his U.S. Pat. No. 3,388,572, which however may have the following drawbacks:
1. When the combination lock is opened by selecting a right opening number of the wheels, the key 50 should be raised to push the element 40 in order to urge the free end 21 of the hasp 17 beyond the lock casing. Since the spring 20 retains the washer 19 secured to a lower end of the hasp 17 to force the hasp 17 downwardly, it requires a bigger force to depress the key 50 in order to open the lock, counteracting the resilience of the spring 20.
2. As shown in his FIG. 1, the key is protruded downwardly when locking the padlock influencing its decorative appearance and increasing its volume inconvenient for handling or storage.
3. The split friction ring 29 is frictionally retained in each wheel 24 so that when resetting a new combination by rotating the wheels 24, the key element 31 formed on the hasp shank 16, as engaged with each ring slot 29' as shown in his FIG. 4 when upwardly supporting the free end 21 of hasp 17 by the key 50, element 40, will firmly hold each ring 29 while rotating the wheel 24, thereby easily causing wearing on a periphery of each ring 29 to lose its frictional engagement with each wheel 24. After using a time period, the wheel 24 may not synchronously drive the ring 29 during rotating the wheels 24 possibly causing a difficulty to obtain an opening combination of the lock.
The present inventor has found the drawbacks of a conventional padlock and invented the present combination padlock easily openable.